Battery Size and other speculation from the EPA numbers

[ajdelange]

What's missing is the rated consumption. We know from the sticker that it "takes" 48 kWh to go a hundred miles but that number, quantized as coarsely as it is is subject to 2.9 Wh/mi uncertainty just from the rounding. Also it has been suggested that this is measured at the plug such that we have the uncertainty in charging efficiency to deal with. If we suppose charging efficiency to be 91 ± 3% it's clear the efficiency dominates and the battery would, for 316 mile range, have to be able to supply between 133.5 and 142.6 kWh. You can now launch into all the speculations as to what the "capacity" of the battery is based on your suppositions about top end and bottom end buffer zones etc. etc.

When the truck hits the customers' driveways we will be able (most probably) to figure out what the rated consumption is and from that get a tighter estimate as to what the actual discharge capacity of the battery is.

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[DucRider]

When the truck hits the customers' driveways we will be able (most probably) to figure out what the rated consumption is and from that get a tighter estimate as to what the actual discharge capacity of the battery is.

Maybe, but discharge capacity is a variable that changes with discharge rate and temperature.

 

[ajdelange]

Maybe, but discharge capacity is a variable that changes with discharge rate and temperature.

Ya, sure and? The estimate of the capacity will still be a random variable but the uncertainty surrounding it will be smaller. Ask yourself which battery parameter is not variable with temperature, discharge rate, hysteresis etc. (hint: there is one).

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